This invention relates to connecting to a network server.
Servers handle (send and receive) traffic on networks such as the Internet. Providing and maintaining a sufficient number of capable servers helps handle the increasing number of users and networks connected to the Internet. One way to provide capable servers involves using scalable servers that can adapt to the changing size of the network(s) they serve. Any number of additional servers can supplement the scalable servers to permit a more even distribution of the load that each server handles.
Another tactic for balancing the load among the servers is server mirroring: providing a primary server and any number of backup servers that duplicate the service of the primary server. These mirrored servers, together called a server farm, may be located in different geographic regions, helping users and networks obtain more localized and reliable service. A round robin system may distribute the load among the servers in the server farm by connecting users and/or networks with the servers on a fixed rotating basis. Additionally, a load balancing system can direct users and/or networks to the servers in the server farm based on the amount of traffic each server can potentially handle and its current load.
Whatever the server configuration, servers use a Network Layer address to route different users and networks across a network such as the Internet. For the Internet, Network Layer addresses are Internet Protocol (IP) addresses. An IP address can be expressed in IPv4 (IP version four) as a thirty-two bit numeric address written as four sets (octets) of three numbers ranging from zero to 255, e.g., 100.50.200.150.
For a given host on the Internet, the most significant bits of the IP address represent the network (wire) it is on, and the least significant bits represent the node upon the network. The exact boundary in the IP address between the network and host parts of the address is specific to the individual network. This is known as the “netmask”.
IP uses hierarchical addressing. This means that in moving up the routing hierarchy, groups of networks are aggregated into larger groups for purposes of routing. These aggregates are known as “prefixes,” and they consist of a set of most significant bits of the address and a number representing the length of the prefix in bits.
Historically, at the top level of the Internet routing hierarchy one could determine the prefix length by examining the most significant bits of the IP address. Up to three of the left-most bits identified the class of a traditional IP address, while the remaining left-most bits identify a particular network (prefix) as shown below:
DecimalNumber ofNetworkRange ofDecimalNumber ofSupportableClass(Prefix)HostNetworkRange ofSupportableHosts perClassBitsBitsBitsAddressesAddressesNetworksNetworkA18240 to 1260.0.1 to12616,777,214255.255.254B21616128.0 to0.1 to65,38465,534191.255255.254C3248192.0.0 to1 to 2542,097,152254224.255.255
In the current Internet, the rules for determining a route to a destination have been nearly or completely replaced by a CIDR addressing scheme using the classless inter-domain routing (CIDR) prefix value. The CIDR addressing scheme increases the number of possible IP top-level prefixes by not limiting the number of network bits to eight (class A), sixteen (class B), and twenty-four (class C).
An example of an IP address with a CIDR prefix is 200.50.75.5/16. The prefix length typically ranges from eight to twenty-eight and indicates the number of bits to identify a particular network, leaving the remainder of the bits to identify hosts on that network. Using CIDR prefix to represent a network increases the number of IP networks over traditional class based IP networks as shown below:
Equivalent Number ofCIDRSupportable Class CNumber of SupportablePrefixNetworksHosts Per Network/8 65,53616,777,216(1 Class A)/9 32,7688,388,608/1016,3844,194,304/118,1922,097,152/124,0961,048,576/132,048524,288/141,024262,144/15512131,072/1625665,536(1 Class B)/1712832,768/186416,384/19328,192/20164,096/2182,048/2241,024/232512/241256/251/2128/261/464/271/832/281/1616